1. Field of the Invention
The invention relates to a method and apparatus for monitoring wind characteristic, such as wind speed, wind direction and air pressure within a volume above an area of land.
The invention is primarily aimed at but not limited to providing services for manufacturers, operators and investigators in wind plant, to monitor existing wind farm sites and also to establish the suitability of proposed sites. The invention may allow the modelling of wind flow and equipment turbulence.
Another field in which the present invention may have utility is the detection of micro bursts and critical wind shears at airports.
2. Description of the Related Art
The siting of wind energy conversion plant has a direct impact on its operating efficiency and profitability. However, current practice in the industry for siting, often relies upon intuitive judgement based upon relatively sparse wind speed measurements and extrapolation along topographical features such as hill crests, valleys and the like. Trial and error methods based on actual performance are also used.
More dense ground coverage by conventional anemometers and the like is often considered too expensive and impractical for site evaluation. Current practices at established wind farm sites may limit the locations of anemometers to the wind plant sites only.
A further problem with wind farms is the effect that the wind plant has on the wind field itself. The extraction of wind energy, coupled with the turbulence caused by supporting towers, nacelles etc., changes the actual wind field characteristics relative to that estimated prior to the existence of the plant.
It is an object of the present invention to alleviate some or all of the above-mentioned problems so that siting of wind energy conversion plants can be optimized for any given topography, wind regime and wind energy conversion equipment.
It is another object of the present invention to enable data indicative of the magnitude of wind characteristics within a volume to be collected at frequent and regular intervals with respect to easting, northing, elevation and time.
It is another object of the present invention to permit accurate imaging of what are termed "wind pressure waves". These waves can be imagined when thought of as waves blowing across a wheat field. These waves are important to wind farm operators as they are the manifestation of the wind irregularity that reduces the quality of electrical power sold by wind farms. The form of these "wind waves" has a very strong linkage to the ground topography, wind direction and speed. Consequently, they are very hard to predict and model. The present invention enables measurement of these wind waves directly and therefore allows appropriate siting of plants so as to minimize the effects of machine induced turbulence, thereby improving the overall efficiency of the wind farm.
It is another object of the present invention to optimize the siting of wind plant in both existing wind farms and proposed wind farms.
It is yet another object of the present invention to permit the detection of desirable wind energy "hot spots" and unwanted turbulence zones or areas of low wind speed.
It is still another object of the present invention to provide the means for recording a large body of wind characteristic data, thereby allowing large scale academic and scientific research to be carried out using the recorded data.
It is still another object of the present invention to provide a data acquisition method, digital electronic data recording and storage means, high speed data processing and computer aided visualization means.
It is another object of the present invention to monitor the magnitude of at least one wind characteristic over a large area without requiring a proportionally large number of wind characteristic measuring means.
It is another object of the present invention to provide an array of wind characteristic measuring means in which the measurement provided by each measuring means is not perturbed by the presence of the other wind characteristic measuring means within the array.
It is another object of the present invention to allow for much denser and more regular coverage and much more frequent time sampling than has hitherto been possible.
It is still another object of the present invention to allow the deployment of large numbers of simple and low cost detectors. This deployment can be at any elevation above ground, dependent upon the scope of the survey objectives.
It is another object of the present invention to permit deployment of detectors at regular intervals in orthogonal directions such that .delta.X and .delta.Y can each be held constant. This will ease the task of any consequent numerical modelling or analysis. As the ground area is adequately covered by a uniform lattice, the gradient, divergence or curl of the characteristic field can be calculated. For example, if the characteristic is pressure, then the gradient is the wind velocity field (i.e. speed and direction) Similarly, if wind speed is being measured, then the gradient of the speed surface may be thought of as the direction.